Access door fitting for tanks



Aug. 27, 1946; F. J. PEPERSACK v ACCESS DOOR FITTING FOR TANKS Filed Aug. 15, 1942 3 Sheets-Sheet 1- fkaxvcllaJ/ zpwsaur,

Aug. 27,1946. F. J. PEPERSACK 12,406,703

ACCESS DOOR FITTING FOR TANKS 3 Sheets-Sheet '2 Filed Aug. 15, 1942 giiiihHw-HW:

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7, 1946. F. J. PEPERSACK 2,406,708

ACCFiSS DQOR FITTING FOR TANKS 3 Sheets-Sheet 3 Filed Aug. 15, 1942 @w a M 1 M Z m w 7? is often convenient or necessary.

Patented Aug. 27, 1946 'e UNITED STATES I aide-hos PATENT OFFICE ACCESS noon FITTING FOR TANKS Francis J. Pepersack, Towson,Md.,' assignor to The Glenn L. Martin Company, Middle River, Md., a corporation of Maryland rigid housing structure. Tanks of thisinature are used as fuel and oil tanks forairplanes. 5 a

They are fitted into the different part of the fuselage or Wings so' that the normal structure provides the rigid housing element of the tank.

An illustration of this practice is found in Gray et a1. PatentiNd 2,102,590 disclosing a cellular "form of tankapplied to aircraft construction.

However, this cellular form of tank is also applicableto other kinds of transport vehicles such as ships, motor trucks, and freight cars.

' Fig. 3; is a vertical transversesection to reduced The general purpose of this invention is to provide a cellular tank of the type indicated with a relatively large access door or closur'e'which vwill facilitate manufacture of the. tank cell and itsassembly, in a housing structure, and also 2 0 afford access to the entire interior of the cell, as i In so doing, it v is desirable to employ a door or closure of the same flexible, rubber-like material as the'cell and to give the cell opening and the door or closure 5 sufiicient'reinforcement so thattheymay be easily assembled together and subsequently clamped in closing relation.

More specifically, it is intended to provide an access door and tank cell opening with a,con-

tinuous, peripherally extending reinforcement which will maintain the shape of both of these parts and yet flex readily in any direction.

An additional object of the invention resides in the provision of opposed clamping elements pro vided with spacing means fOr preventing undue compression of the cell material which is often of a rubber subject to cold flow deformation.

A further specific object is to modify the construction of the tank cell around its opening and the access door around its periphery so as to replace a portion of the cell-construction which is most susceptible to cold flow with a material which is resistant thereto.

A further object of the invention, the details of which will be pointed out subsequently, is to provide a form of clamping means for the tank cell and access door which may be used without modification for tank cells of widely varying thickness withthe addition or subtraction of a molding strip of resilient material.

One of the more specific objects is to provide a special form of threaded means which may be f Application August '15, 1942, Serial Nq i'ssess 5 Claims. (01. 1'5o 3) v thetank'cell on the rigid housing structure and assist in the assembly of the acces door. 'Still other features of novelty contributing to the efiiciency and simplicity of the fitting construction of this invention, will be pointed out in connection with the following detailed description of severa illustrative embodiments taken in connection with the accompanying drawings, in

which i Fig. 1 shows a fragmentary plan view of an access door fitting for a circular tank opening, the view being partly broken away to show certaindetails in section; 1 I

Fig; 2 i a fragmentary plan view of a clamp ing member of the fitting;

Fi .8 showspartially in elevation and partially *inftransverse section a special form of clamping means and hanger arrangement for the tank cell.

Referring to Figs. 3 and 4, a tank cell of flexible rubber-like materia1 is designated generally as l0 and is provided With a rigid housing structure l2 which'in this instance is the surface structure of an aircraft. It will be noted that the tank cell'Hl is'formed to provide a relatively large opening I4 which i circular in the illustrated embodiments. An acces door iii of the. same or similar material a the tank cell, is made 0 slight1y smaller and'of the same shape as the opening l4 into'which it is fitted.

An outer clamping flange l8 and an inner clamping flange 2i] engage the corresponding sides of the tank 'cell 10 and door or closure i6 50 as to span their juncture and clamp thesetwo tank cell part in sealing relation. The outer circular clamping flange I8 is provided with a series of spaced holes 22 for receiving the shanks of a set of screws 24 which are threadedly engaged in a correspondingly spaced set of tapped bosses 26 formed on the inner clamping flange gripping edges 28, 28 and a series of gripping used with the cell clamping; members to support ridges or similar formations .30, 30. Flange 20 3 ha identical projections in the form of gripping edges 32 and gripping ridges 34 acting in opposition to those of the clamping flange l8.

A particular feature of the inner clamping flange 29 is a series of spacer elements 36 extending between the screw holes 22, as shown best in Fig. 2. The spacer elements 36 are preferably of arcuate shape or may be of short lengths and arranged on the arc of a circle having the radius of the centers of the screw openings 22. It is the function of the spacer elements 36 to fit between the peripheral edges of the tank cell 10 and the access door [6, and to engage the opposite part of the outer clamping flange l8 so as to limit the threaded screws 24 toa predetermined clamping engagement with the compressible tank cell and door material. 7

Figs. 1, 3 and 4 show the manner in which the opposed peripheries of the tank cell ii] and the access door of closure 3 are reinforcedby means of a hoop 38 andan identical but slightly smaller hoop 41!, respectively. Preferably, the tank cell hoop 38 and the door hoop 4e are of rectangular cross-section andformed of braided steel wire impregnated and covered with a synthetic rubber material such as neopreneflor other equivalent material. As used herein, the term hoop is not limited to a circular ring, but denotes a continuous element having the configuration of the tank cell opening I l.

The tank cell IE) is of the self-sealing, bulletproof type specifically disclosed and claimed in Gray and DeWeese patent application Serial No. 338,052, filed May 31, 19410, entitled Self-sealing tank. The cell ll! comprises four principal layers which are adhesively bonded together and arranged in the manner shown. These layers are a soft, vulcanized outer layer 42, a middle layer cell I0, it is believed unnecessary to repeat those details.

The clamping means and tank cell opening and access door reinforcements which have been described with respect to the illustrative embodiment of Figs. 1 to 4 may be adapted without modification to a tank cell 58 of single layer construction. The tank cell 53 shown in Fig. 5 is provided with an opening 6!] for receiving an access door 52. The tank cell 58 comprises a thin wall layer 64 of flexible rubber-like material such as neoprene or other synthetic rubber, which is resistant to the action of liquid hydrocarbons.

. Abo-utthe opening 69 the rubber-like layer 6 1 is d4 of crude, unvulcanized rubber which is subject to cold flow and loss of shape under continued clamping pressure, a highly, liquid hydrocarbon resistant, inner layer of neoprene or equivalent synthetic rubber composition, and a relatively thin, inner liner layer 48 composed of a strong fabric impregnated with neoprene, or equivalent non-fabric material. Becauseof susceptibility to cold flow, the middle layer-M: of crude unvulcanized rubber is replaced by a circular layer 58 extending as a ring about the tank cell opening I l. The circular layer of filler element to is preferably formed of fabric impregnated with neoprene or other synthetic rubber-like material of equivalent properties.

Means for retaining the reinforcing hoop 38.

in position around the periphery of the tank gcell opening it are shown in Fig. 4 as comprising a braid reinforcement 52 which is wrapped around the edge of the opening so as to cover the hoop 38 and extend over the inner and outer surfaces of the tank cell [0. This braid reinforcement or continuous binding is impregnated with neoprene or the like and secured in the position shown by Fig. 4. The outer side of the tank cell NJ has a seam cover 54, of balloon cloth fabric impregnated with neoprene or the like, and provided with an upstanding flange 56 extending within the space between the tank cell opening l4 and the spacer elements 36, or clamping screws 24. This seam cover 54 will also be secured in place by a suitable adhesive. Since the means for securing the door reinforcing hoop 4B in position and the construction of the door I6 around its edge are identical with that which "have been described for the opening of the tank faced and reinforced by identical inner and outer layers 68 and 68, respectively, adhesively secured thereto and composed of heavy fabric material impregnated with neoprene or the equivalent. By reason of the much less thickness of the tank cell 58, it is necessary to provide a resilient molding or filler strip "it, of any suitable rubber material which willtake up the space and permit the use,

of the same clamping flanges wand 26 previously described. The outer surface of the door 52 will also be provided with a molding or filler strip 12 about its periphery and extending beyond the point of contact with the outer clamping flange The reinforcement of the tank cell opening 59 and the periphery of the door 62 is by means of hoops l4 and i6; respectively, whichare identical with those which have been disclosed in connection with the principal embodiment. ,Correspending use is also made of an impregnated braid reinforcement 13 as retaining means for the cell hoop 74, it being noted that the molding or filler strips l9 and M are provided with adhesively secured fabric reinforcements 8c and 82 on their respective inner faces. An outer reinforcement layer 84, preferably'of balloon cloth fabric impregnated with neoprene, covers the outer end of the braid reinforcement 18 and is provided with an upstanding flange 66 extending generally parallel with the thickness of the hoop 7A. As will be appreciated from an inspection of Fig. 5, the door or closure reinforcing hoop troughlike recess N32 for receiving the heads of the threaded clamping screws, the other ends of which threadedly engage an inner clamping flange'zeil in the same way as has been set forth. It will also be noted that the clamping flanges I and 208, which are of circular shape to correspond with the cell opening, lack the intermediate clamping ridges used in Figs. 3 and 4.

With reference to Fig. '7, the inner clamping flange 299 is further modified in its provision for a spaced series of transverse holes or openings 202 through its web 2134 for permitting free drainage of gasoline or other liquid hydrocarbon.

In Fig. 8 there is shown a special screw or bolt 246 which functions both as a threaded clamping .means for the outer and inner flanges 89 and clamping means shank'part'fld may be'turned into the inner clamping member 200 to draw it toward the outer clamping member I80. The outer end of the bolt 24il'hasa larger threaded shank 248 engaged by a wing nut250 and locked by a wire 252 when clamped'down upon the plane portions of the structure l2 through van intermediate clamping Washer 254. In this manner, the tank cell Ill and its access door or closure I6 are secured or hung to the rigid housing structure l2. 'i' t It will be apparent that the modified form of illustrated in Figs. 6, '7; and 8 may be" applied either to the multiple layer cell I or to thesinglelayer tank cell'58 with the use of rubber molding or fillers-I0 and I2.

The access door fitting 'whichfhas been de-, scribed in detail is readily attachedtothetank cell and an 'adequate, but non-destructive, sealingis obtained with theclamping means of this invention. With the special form of cell opening and door edge defining hoops of this invention, the mating edges are fully protected against tearing and damage so that the access door may be removed and replaced as often as may be necessary.

While a circular access door fitting has been shown illustratively, other forms of opening and fittings may be employed as convenient. It will also be understood that various changes may be made in the details of construction and arrangement of the elements of this fitting without departing from the spirit of the invention and the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. An access door construction for a flexible, rubber-like tank cell provided with a relatively large generally circular opening in its wall, comprising, a door of the same material as the tank cell fitted within said opening,'a first flexible hoop of reinforced, rubber-like material positioned against the periphery of the circular opening of the tank cell, means for securing said first flexible hoop to the tank cell, said means comprising a continuous strip covering said hoop, said strip being secured to the inner and outer surfaces of said wall around said opening, a second flexible hoop of reinforced, rubber-like material extending around the periphery of the door, similar means for securing said second flexible hoop to the door, a continuous outer clamping flange spanning the juncture between the tank cell and the door, a continuous inner clamping flange arranged in opposition to the outer flange, spacer elements on one of the clamping flanges and extending between the two hoops for limiting the clamping action of the clamping flanges on the tank cell and the door, and separable means engaging the clamping flanges between the spacer elements to maintain them in clamping position.

2. An access door construction for a liquid fuel or lubricant tank cell comprising one or more layers of rubber-like material subject to cold flow and provided with a relatively large opening in its wall, comprising, a door of the tank cell material fitted within said opening, a first flexible hoop of reinforced, rubber-like material positioned against the periphery of the 6 of reiniorced,-rubber-like material extending around the periphery of the door, similar continuous binding means for securing said second flexible hoop to the door, an outer clamping flange spanning the juncture between the cell opening and the door, an inner clamping flange arranged in opposition to the outer flange, means at spaced positions on one of the clamping flanges and extending between the two hoops for limiting the clamping action of the clamping flanges on the tank cell and the door, and detachable threaded means engaging the clamping flanges to. maintain them in [clamping position, said clamping flanges beingformed with opposed pro-- jections for gripping the tank cell and the door. 3. The combination comprising a hydrocarbon licijid container cell formed of three layers of "rubber-like} material, the intermediate layer of which'issubject-tocoldflow, said tank cell being 'provide'dwith a relatively large opening in its wall, a closure of the tank cell wall material fitted within said opening, a first ring-shaped filler layer of material resistant tocold flow inserted between two of the layers of rubber-like material around the tank cell opening and in place of the intermediate layer, said intermediate layer being cut away from the tank cell opening to receive the first filler layer, a second ring-shaped filler layer of material resistant to cold flow inserted between two of the layers of rubber-like material around the periphery of the closure and in place of the intermediate layer, said intermediate layer being cut away from the closure periphery to receive the second filler layer, a binder strip secured to the inner and outer faces of said closure around said opening, an outer clamping flange coextensive with the tank cell opening and spanning the juncture between the tank cell opening and the closure, an inner clamping flange coextensive with the tank cell opening and arranged in opposition to the outer flange, means on one of the flanges and extending between the cell opening and closure peripheries for predeterminedly limiting the clamping action of the flanges on the tank cell and the closure, and separable means engaging the clamping flanges to maintain them in clamping position.

4. The combination comprising a hydrocarbon liquid container cell 'iormed of three layers of rubher-like material, the intermediate layer of which is subject to cold flow, said tank cell being provided with a relatively large opening in its wall, a closure of the tank cell wall material fitted within said opening, a first ring-shaped filler layer of material resistant to cold flow inserted between two of the layers of rubber-like material around the tank cell opening and in place of the intermediate layer, said intermediate layer being cut away from the tank cell opening to receive the first flller layer, a second ring-shaped filler layer of material resistant to cold flow inserted between two of the layers of rubber-like material around the periphery of the closure and in place of the intermediate layer, said intermediate layer being cut away from the closure periphery to receive the second filler layer, a binder strip secured to the inner and outer faces of said cell wall and said closure around said opening, an outer clamping flange coextensive with the tank cell opening and opening of the cell, continuous binding means spanning the juncture between the tank cell opening and the closure, an inner clamping flange coextensive withthe tank cell opening and arranged in opposition to the outer flange, means on one of the flanges and extending between the cell opening and closure peripheries tor predeterminedly limiting the clamping action of the flanges on the tank cell and the-closure, separable screws engaging the clasping flanges to maintain them in clamping position, and a rigid housing structure confining the tank cell, the closure, and the clamping flanges, at least one of said screws having a nut threaded on one end and a Washer thereunder for engaging and hanging the tank cell to the rigid housing structure.

5. An access door construction for a single layer, flexible, rubber-like tank cell provided with a circular opening in its wall, comprising a door of similar material to the cell fitted within said opening, a resilient molding strip of appreciable thickness secured to and facing thetank cell layer around its opening, another resilient molding strip of appreciable thickness secured to and facing the door around its periphery, a first flexible hoop of reinforced, rubber-like material positioned against the periphery of the circular open- 8 .ing of the tank cell, meansfor securing said first flexible hoop to the tank cell and its molding strip, said means comprising a continuous binder strip covering said hoop, said strip being secured to the inner and outer surfaces of said cell wall and molding stri around said opening, a second flexible hoop of reinforced, rubber-like material extending around the periphery .of the door,.similar means for securingcsaid second flexible hoop to the door and its molding strip, an outer clamping flange spanning the juncture between the cell opening and the door, an inner clamping flange arranged in opposition to the outer flange, means on one of the clamping flanges and extending between the two hoops for predeterminedly limiting the clamping action of the clamping flanges, and detachable threaded means engaging the clamping flanges to maintain them in clamping position. I

FRANCIS J. PEPERSACK. 

